Figure 5.

Raman mapping images of R6G on MoS₂/patterned Si substrate at different concentrations: (a) 10⁻³ M, (b) 10⁻⁴ M, (c) 10⁻⁵ M, and (d) 10⁻⁶ M, overlaid with corresponding OM images. The signal intensity decreases as the concentration reduces, with strong and uniform signals observed at higher concentrations (10⁻³ M), while the signals are significantly weaker at lower concentrations, indicating the detection limit around 10⁻⁵ M.